The objective of this study was to analyze gene alterations of the brain lymphomas and, based on the results which might be specific for a given individual tumor, to investigate the original cells of this tumor. For this sake, cloning and nucleotide analysis of the rearranged regions of the immunoglobulin genes were performed, first. In this case, however, since we used tumor tissue samples, it was required to compare various cloning techniques and to establish and use the most suitable technique to avoid a possibility that we might clone DNA from reactive lymphocytes which coexist frequently in neoplastic tissues. After the comparison of various cloning techniques, we found that a combination of successive procedures consisting of electrophoretic fractionation of restriction enzyme-digested genomic DNA,PCR-amplification, cloning and comparison of clones among fractions was most simple, rapid and reliable. Actually, we have determined nucleotide sequences of rearranged regions of immun
… Moreoglibulin genes in a number of brain lymphoma cases by this approach (manuscript in preparation). The nucleotide sequences obtained were useful to eaxamine whether or not the neoplastic cells were derived from the same orgin and also to search whether or not the same cells were present, if not proliferating, in generalized lymphatic apparatus. In this study, we also examined tumor suppressor genes in brain lymphomas and detected p53 mutations in 60-80%, 15 and p16 gene mutations in 60-80% of cases, but p21 gene mutation in none of cases examined. These mutation were compared with those in various brain tumors other than brain lymphomas. In addition, we have cloned human gene of 2', 3'-cyclic nucleotide 3'-phosphodiesterase which was expressed in oligodendrocytes and also in lymphocytes and determined the gene structure and its chromosomal localization. Attempt to establish brain lymphoma cell lines was also performed and obtained 2 cell lines and immunoglobulin genes of which were examined by the same method described. Less